1. Field of the Invention
The present invention relates to an electrophotographic photosensitive member, and a process cartridge and an electrophotographic apparatus each having an electrophotographic photosensitive member.
2. Description of the Related Art
An electrophotographic photosensitive member which contains an organic photoconducting material is predominantly used as the electrophotographic photosensitive member to be installed on a process cartridge or an electrophotographic apparatus. In general, an electrophotographic photosensitive member includes a support and a photosensitive layer which contains an organic photoconducting material on the support. The photosensitive layer is typically of a lamination type (sequential layer type), formed of a charge-generating layer and a charge-transporting layer laminated in this order from the support side.
In an electrophotographic process, the surface of an electrophotographic photosensitive member comes in contact with various materials (hereinafter referred to as “a contact member”) such as developer, a charging member, a cleaning blade, paper, and a transfer member. Examples of required characteristics for an electrophotographic photosensitive member therefore include reducibility of image deterioration due to contact stress with a contact member. In association with recent improvement in durability of an electrophotographic photosensitive member, further improvement is required in sustained effect of reduction in image deterioration due to the contact stress and in potential stability (reduction in potential variation) for repeating use.
Regarding sustained contact stress relaxation effect and potential stability for repeating use of an electrophotographic photosensitive member, a method for forming a matrix-domain structure in a surface layer using a siloxane resin having a siloxane structure integrated into a molecular chain is disclosed in International Publication No. WO2010/008095. According to the method, the use of a polyester resin having a specific siloxane structure allows for both of the sustained contact stress relaxation effect and the potential stability for repeating use of an electrophotographic photosensitive member.
The electrophotographic photosensitive member disclosed in International Publication No. WO2010/008095 achieves both of the sustained contact stress relaxation effect and the potential stability for repeating use.
However, the present inventors have found requirements for further improvement in the image deterioration caused by a photo memory due to a potential difference between a portion irradiated with light and a portion not irradiated with light.